China is mounting a serious effort to challenge US military superiority in air and space, forcing the Pentagon to seek new technologies and systems to stay ahead of its rapidly developing rival, Deputy Defense Secretary Robert Work said on Monday.

The Pentagon’s chief operating officer, speaking to a group of military and civilian aerospace experts, said China was “quickly closing the technological gaps,” developing radar-evading aircraft, advanced reconnaissance planes, sophisticated missiles and top-notch electronic warfare equipment.

While hoping for a constructive relationship with China, the Pentagon “cannot overlook the competitive aspects of our relationship, especially in the realm of military capabilities, an area in which China continues to improve at a very impressive rate,” he said.

Work made his remarks to the inaugural conference of the China Aerospace Studies Initiative, a partnership of the US Air Force and the RAND Corporation think-tank. The initiative aims to boost US research on China’s aerospace ambitions.

The conference came as hundreds of Chinese officials were in Washington for the three-day US-China Strategic and Economic Dialogue, wide-ranging talks that look at areas of mutual cooperation even as they address points of friction.

Asked about the timing of the military conference, Work said US and Chinese leaders both see the bilateral relationship as one in which there are “measures of cooperation and measures of competition.”

“We’re hoping over time that the cooperative aspects outweigh competitive aspects,” Work added. “As the Department of Defense, we’re the hedge force. … We say, ‘Look, here are capabilities that we see that the Chinese are developing and it’s important for us to be able to counter those.”

Work, citing a Harvard study on rising powers confronting established powers, told the conference that interactions between the two often result in war. As a result, the Defense Department must “hedge against this international competition turning more heated.”

The United States has generally felt the best hedge is a strong nuclear and conventional deterrence capable of overmatching any rival, he added.

Work said the United States has relied on technological superiority for the past 25 years, but now “the margin of technological superiority upon which we have become so accustomed …is steadily eroding.”

To adjust, he said, the Pentagon is working to develop new technologies to maintain its edge and lower the cost of responding to attacks. Directed energy weapons, for example, might be able to shoot down missiles that cost a hundred times the price of a jolt of energy.